Expansible container for lowtemperature fluid



July 12, 1960 J. H. FARRELL 2,944,692

EXPANSIBLE CONTAINER FOR LOW-TEMPERATURE FLUID Filed March 2'7, 1958FIG. 2

} uvvmrons James A! Farm BY A/exls Pasfu/mv ATTORNEYS Unite EXPANsmLacoNrArNER FOR LOW-,

James HQ; Farrell, Arlington, and Alexis Pastuhov, Harassignors, bymesne'jassignments, to (3011- vard, Mass, stock Liquid MethaneCorporation, New York, N.Y., a corporation of Delaware Filed Mar. 27,195$, S er.'No.72 4,443

- 9 Claims. (Cl. 220 -9) This invention relatesto storing and shippingliquefied gases at low' temperatures and'moreparticularly to the StatesPatent rounding the walls for support,

Patented mini 32, 1%80 7 2 weight and cost of the storage or'shippingtank. One way in which the tank may be made to meet these requirementsis to make some portions'of the tank expansible. It is therefore anobject of this invention to provide a tank, suitable for storing andshipping liquefied gases,

which maybe constructed of thin metal walls, thus resulting in lowerconstruction costs.

It' is another object to provide receptacles, suitable for. storing andshipping liquefied gases, which can re main continuously in contact withinsulating material sur- It is another object to provide an innerreceptacle for storing, and shipping liquefied gases which depends for aportion of its structural, support upon an outside receptacle.

It is a furtherobject of this invention to provide re- 1 ceptacles,suitable for storing and shipping liquefied gases,

cient of thermal expansion and hence is subject to -contraction andexpansion when exposed to temperature 1 changes. The problem ofexpansion and contraction becomes markedly acute at the temperaturesnormally encountered in thehandling of liquefied gases because thetemperature differential between the liquefied gas temperature andnormal room temperature is very great.

In the case where the inside tank designed for storing or shippingliquefied gases is completely surrounded by 1 an insulating material,such as balsa or cellular glass for example,'contraction of the tankwalls when the liquefied gas is added means that the walls pull awayfrom the insulating material leaving a void area between the outsidewall of the tank and the insulation material. There are cases where itis desirable to design the inside tank, containing the liquefied gases,so that itiwill depend for support upon the layer of insulation materialand the outside wall of the receptacle surrounding the insulationmaterial. When this'is desirable, it may readily be seen that gapsbetween the walls of the inside tank and the insulating material wouldlead to stresses in the tank walls brought about by the removal of theneeded structural support otherwise ofiered by the outside receptacleand the insulation material andby the pressure of the liquid and/or ofthe gas within the inner tank. Repetition of the cooling-warming cycle,brought about by the addition and removal of the liquefied gas, andhence the stresses set upafter a relatively short period, may cause 'theinner tank to fail. This is particularly true when the inner tankisintentionally fabricatedot thin gauge metal which is incapable byitselt of maintaining shape under the liquid and/ or pressure load.

. Moreover, if the inner tank containing the liquefied gas is onlypartially. filled a large temperature gradient will existin the gascolumn above .the liquid level. -T his means that the tank wallswillalso exhibit-a marked temperature gradient approximating the temperaturegradient in the gas because of the very low thermal conductivity ofmetal walls at the low temperatures involved. The resulting temperaturegradients introduce additional stresses in the walls which may bepartially relieved by the tank design of this invention.

It therefore becomesevident that it would be desirable to have metalstorage tanks which have relatively thin metal walls and which candepend upon the outside receptacle for structural support, thus reducingthe which are expansible under the hydrostatic load and/or under thepressure built up within the receptacle by the vaporization of theliquid into gas.

These and other objects will appear in the following discussion which ispresented with reference to, the accompanying drawing in which Fig. 1represents a cross-sectional view of the type of tank construction towhich this invention is applicable; Fig. 2 is a diagrammatical View offour walls of the expansible tank of this invention, and r Fig. 3 is adetail drawing of the welding'of the expansible members.

'By the process of this invention, atank suitable for storage andtransportation of liquefied gases is made expansible to allow the sidesof the tank to remain substantially continuously in contact with theinsulation layer and hence makefuller use of the additional'structuralsupport oiiered by the insulation layer and/or the outside receptacle.The tank is made expansible by the con struction of the tank ofprismatic shape with a corner portion in the form of a stapped member,hereinafter identified as a bellows type arrangement, joining thevertical walls, and by providing a stiffening or reinforcing member inthe base portion of the bellows to pre vent collapse, particularly whenformed of a highly resilient and deformable material. The bellowsconstruction employed to join the side walls of the tank and to form thecorner portions therebetween may also be employed in the top and bottomWalls to permit the corresponding type of expansion and contractionwithout the development of stresses otherwise occasioned by themovements which would take place in the side Walls. Therectangular'bellows permit each of the walls and the roof and bottomwall to move in a direction normal to its own plane when it is subjectedto a slight pressure by the gas or liquid contained within the tank tocompensate for the change in dimension upon expansion or con.- tractionof the metal thereby to enable the walls to remain substantiallycontinuously incontact with the layer of insulation for support.

The expansible tank of this invention may be further explained withreference to the figures.

In Fig. 1 there is shown a simplified cross-sectional view of thegeneral type of tankusedfor storing or ship ping liquefied gases. Thetank will be a polyhedron configuration and preferably one *which is arectangular parallelepiped. The inner tank 10, designed to contain.

the liquefied gas 13, is placed within a surrounding vessel 11 andinsulating'rnaterial lz placed between them.

Such a tank may be equipped with a filling line 22 in which is placed apressure-regulatingvalve 21 to provide proper gas venting, and with adraw-off line 19 incorporating valve 20. When the sides, top and bottomof tank 10 press closely on the insulating material, tank 10 forms anintegral unit with tank 11 and tank may therefore be of a lighterweight, thinner construction than if this integration did not exist.When the walls of tank 10 are cooled by the introduction of theliquefied gas, theycontract, 'if made in the conventional manner, and.,pull away from'the insulation and destroy the necessary'integration andinteraction.

'In a tank such as shown in Fig. 1 the surrounding vessel 11 may beeliminated where insulation 12is of such structural material,'forexamp'le, cellular glass, cork orbalsa wood, that it forms a strongoutside receptacle.-

In such a case bymaintaining the tank walls 10 in contactwith'insulating material '1'2,"a strong integral unit is achievedwithout the additional tank 11.

In Fig. 2 it is shown how four walls of the inside tank 10 which"actually contain the liquefied gas are made expansiblelin accordancewiththe practice of this invention. The tank of'Fig. 2"has a rigid frame17 made of stiffening members. Tank wall 16 is connected to the tankframe'17 by. meansof rectangular bellows 18 which are welded orotherwise joined at their lines of contact-with frame 17. Sufiicientfreedom of movement is provided by the convolutions of the bellows topermit wall 16 to move back and forth from its corresponding framemember 17 in a direction normal to the plane of the wall. In similarfashion the top of the tank may also be connected by means-of bellows.It is not necessary to equip the bottom of the tank with an expansiblewall since the weight of the liquid contained will be sufficient to keepthe bottom tightly pressed against its insulation. Furthermore, thebellows, if they are used on the bottom wall, would normally always becontracted.

Fig. 3 illustrates in detail an example of a rigid member and the way inwhich the bellows 18 may be joined to this member 17 and tank wall 16.Other .forms of rigid members, such as ,I beams, may be used equallywell.

The components, including walls, stiffening members and bellows, of thetank of this invention are conveniently constructed from stainlesssteel. However, other suitable metals, such as aluminum or'alloys, whichpossess the desired structural strength, may be used.

The numberof bellows, their size and thickness of bellows materials willbe determined by the design conditions set for the system. 'In general,the number of bellows is anfunctionof the thickness of bellows material,the pressures at-which they must work, the extension ofthe wallsrequired and upon the stresses involved, the higher the stressesthefewer bellows required. As an example of the number of bellows whichmay beused, assume a tank which is 33.,feet by 28 feet at the base and50 feet high. In such a tank, if the bellows material is 0.05 inchthick,a bellows with 44 convolutions would be considered advisable vwhile ifthe bellows material is 0.125 inch thick, some .18 .convolutions are.desirable.

The size of-the tanks to which the expansible sides of this .inventionare applicable will vary with design-conditions, .particularly with theinternal .pressure the tank. .That is, the. .higher the internalpressure, .the smaller the tank should be to prevent racking of thebellows. The .extensionofthe bellows is alsodependent upon the size ofthe tank. .The larger the tank, the greater extension required.

The bellows may be formed by anysuitable means such as byweldingsections together along their longitudinal .edges or by foldingthe convolutions to shape. The bellows .are'then preferably welded tothe supporting means and the tank walls .to form the completed tankwhich is hermetically =sealed to contain the liquefied gas.

The supporting or stilfeningmember -17 may comprise an elongate:membenofrectangular shape, as shown, but it may equallycompriseenelongate member of baror polygonal shape. In the preferrediembodil'flfillt, the stiffening member is arranged with one-of its;fiat sides in abutting relationship with the flat face innermost in thecorner construction embodying the expansible bellows. It will beapparent that the stifiening member can also be fixed to the bellowsportion along one of the edges or corner portions of the stiffeningmember, as shown in Fig. 4, thereby to provide for still greaterresiliency or deformation in the wall construction without sacrifice ofrigidity or support. It is preferred to embody the bellows as a cornerof the polyhedron but it will be apparent that the'bellows canbeincorporated into a wall-portion :intermediate its ends, asillustrated 'in thetop wall in Fig. 3. While it can extend outwardlyfromthe top wall, it would be apparent that in the'side and bottom walls ofthe tank the bellows would extend inwardly into the tank.

Thus, by the use of the expansible tanks of this invention, there areprovided meansfor continuously keeping the outside of the tank walls incontact with the insulating material surrounding the tank which in turnmeans that thin-walled tanksmay be used since the tank can..bestructurally supported by the insulation and the outside tank or by theinsulation alone.

We claim: a V

1. A tank for the storage of aliquid, theflboiling point of whichdiflers widely from the ambient temperature, consisting of an innershell housing said liquid and which is subject to noticeable expansionand contraction due to temperature changes, a thermal insulatingmaterial surrounding the inner shell, said inner shell'having the shapeof a polyhedron and being provided with an expansible member at each ofa plurality of the edges of the sides of said polyhedron, each suchexpansible member being in the form of a bellows member, each suchbellows member being hermeticallysealed along one edge to the contiguousedge of the side which it joins, a rigid member disposedparall'el tosaid contiguous edge and secured thereto, the rigid members of saidedges of said polyhedron constituting a supporting framefor-saidpolyhedron, whereby the inner shell remains continuouslysubstantially in contact with theinsul-ating material.

2. A tank according to claim '1 wherein said inner shell is coated witha-thermal'insulating'material'having structural strength.

3. A tank according to claim 1 wherein an outershe'll surroundsand'remains continuouslyin contact with the insulating material.

4. A tank according'toclaim 1 whereinsaid inner shell is a rectangularparallelepiped.

'5. A tank according to claim 1 wherein all of the edges of the sides ofsaid inner shell are provided with said expansible member.

6. A tank according to'claiml wherein a frame defines the shape of saidinner shell, said frame comprising a plurality of straight rigid membersand supporting the side of said inner shell, each of a plurality of theedges of said sides being'hermetically'joined to "said-frame by means ofa bellows member. 7

7. A tank according to claim 1 wherein-saidbellows members extendoutwardly from the inner 'shell.

.8. A tank according to claim l-wherein'said bellows membersextendinwardly into the inner shell.

9. A tank of largecapacity' 'for the sto-rage'of a liquefied natural gasat about atmospheric pressure consisting of an inner shell-formed ofmetal capable of retaining its ductility -atthe low temperatureof theliquefield 1 gas and which is subject tochange'in'dimensionsdue toexpansion and contractionin-response-to temperature change, an outershell surrounding the inner shell in-spaced relation'therewith toprovide an open space'in-between filled with thermal insulatingmaterial, said inner shell having the shape of a polyhedron which'isformed of thin-metal walls, an expansible member :at each of a pluralityof the edges ofthe sides of saidpolyhedron, eachssuch :expansiblememberbeing in .the form. of abellowsymember, each such-bellows memberextending .inwardlyzinto the inner shell-and beinghermetically sealedalongiits' sedges r 5 to the contiguous edges of the side adjacentthereto to interconnect the adjacent sides in sealing relationshiptherebetween, a rigid member disposed parallel to said contiguous edgeand secured thereto, the rigid members of said edges of said polyhedronconstituting a supporting I frame for said polyhedron, whereby the innershell remains continuously substantially in contact with the in-References Cited in the fileof this patent UNITED STATES PATENTS MooreMay 10, 1892 Ziebold June 25, 1957

